JP6690712B2 - Torque control method and torque control device - Google Patents

Description

  The present invention relates to a torque control method and a torque control device.

  BACKGROUND ART Conventionally, an electric vehicle equipped with a traveling electric motor includes an accelerator sensor, a vehicle speed sensor, and a controller that controls the torque of the traveling electric motor. The controller calculates the average accelerator amount from the accelerator operation amount detected by the accelerator sensor, calculates the target driving force of the driving wheels from the vehicle speed, the accelerator operation amount, and the driving map, and calculates the target driving force and the CVT transmission. From this, the target torque of the electric motor for traveling is calculated. Then, the controller controls the traveling electric motor so as to generate the target drive torque from the traveling electric motor (Patent Document 1).

Japanese Patent Laid-Open No. 05-168108

  However, in the above electric traveling vehicle, when the motor is controlled so that the output torque of the motor becomes the required torque when the required torque from the driver is small, there is a problem that the driving efficiency of the vehicle is low.

  The problem to be solved by the present invention is to provide a torque control method and a torque control device that improve the operation efficiency of a motor.

  The present invention calculates the required torque of the motor, controls the torque generated in the motor based on the required torque, sets the required torque to zero when the required torque is smaller than a predetermined torque threshold, and sets the set required torque. The above problem is solved by controlling the motor based on the above.

  According to the present invention, the operating efficiency of the motor can be improved.

FIG. 1 is a block diagram of a vehicle system having a torque control device according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of the driving force map. FIG. 3 is a flowchart showing the control flow of the torque control method according to this embodiment. FIG. 4 is a diagram showing a peripheral portion of the area A in the driving force map shown in FIG. FIG. 5 is a diagram showing changes in torque and vehicle speed for each step on the driving force map shown in FIG. FIG. 6 is a time chart of turning on and off the inertia traveling control and a graph showing a torque characteristic. FIG. 7 is a time chart of turning on and off the coasting control and a graph showing torque characteristics. FIG. 8 is a graph showing torque characteristics in the normal mode. FIG. 9 is a graph showing the torque characteristic in the normal mode and the torque characteristic in the eco mode. FIG. 10 is a graph showing the characteristics of power loss with respect to the motor rotation speed. FIG. 11 is a graph showing a characteristic of efficiency with respect to motor rotation speed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram of a vehicle system including a torque control device according to this embodiment. The torque control device according to the present embodiment is a device that controls the output torque of a drive mechanism included in a vehicle, and is provided in the vehicle. In the following description, the case where the torque control device is installed in an electric vehicle is described as an example. The torque control device does not necessarily have to be mounted on an electric vehicle, and may be mounted on another vehicle system such as a hybrid vehicle or a drive system other than the vehicle.

  As shown in FIG. 1, the vehicle system includes a drive wheel 1, a differential gear 2, a generator (MG: motor) 3, a rotation speed sensor 4, an inverter (INV) 5, a battery 6, a motor controller 7, a battery controller 8, An accelerator opening sensor 9, a vehicle controller 10, and a memory 11 are provided.

  The drive wheel 1 rotates by the power output from the generator 3. The differential gear 2 transmits the power of the generator 3 to the left and right drive ratios. The generator 3 is the drive source of the vehicle system and is driven by the electric power of the battery. The rotating shaft of the generator 3 is connected to the axle. During powering of the generator 3, the torque generated by the generator 3 is transmitted to the drive wheels 1 via the axle. When the generator 3 is regenerated, the generator 3 uses the rotational force of the driving wheels 1 to generate power, and the battery 6 is charged with the generated power.

  The rotation speed sensor 4 detects the rotation speed of the motor 3. The rotation speed sensor 4 outputs the detected value to the motor controller 7.

  The inverter 5 is connected to the generator 3 by three-phase wiring, and is connected to the battery 6 by a power line. The inverter 5 converts the output power of the battery 6 into AC power and outputs the AC power to the generator 3. The inverter 5 also converts the power generated by the generator 3 into DC power and outputs the DC power to the battery 6. The inverter 5 has a circuit in which switching elements (power modules) such as IGBTs are connected in a bridge shape.

  The battery 6 is composed of a secondary battery such as a lithium ion battery. The battery 6 functions as a power source of the vehicle system.

  The motor controller 7 is a controller for controlling the generator 3. The motor controller 7 controls the generator 3 based on the required torque output from the vehicle controller 10 and the detection value of the rotation speed sensor 4. The motor controller 7 uses the rotation speed sensor 4 to calculate the rotation speed of the generator 3. The motor controller 7 calculates a command value for the output torque of the generator 3 to match the torque command value at the current rotation speed of the generator 3. The command value is represented by a current command value or the like. The motor controller 7 feeds back a detected value of a current sensor (not shown) to match the output torque of the generator 3 with the torque command value, and calculates the command value by PI control. The motor controller 7 generates a switching signal by comparing the calculated command value with the carrier, and outputs the switching signal to the inverter 5. The switching signal switches on and off of the switching element included in the inverter 5. Signal. As a result, the motor controller 7 controls the torque generated by the generator 3 based on the required torque (required torque for control) output from the vehicle controller 10.

  The battery controller 8 is a controller for managing the state of the battery 6. The battery controller 8 manages the battery 6 by calculating an SOC (State of Charge) using a voltage sensor (not shown) connected to the battery 6. The battery controller 8 outputs a signal indicating the state of the battery 6 to the vehicle controller 10.

  The motor controller 7 and the vehicle controller 10 and the motor controller 7 and the vehicle controller 10 are connected by a CAN bus. The CAN bus is a communication network that connects the controllers mounted on the vehicle.

  The accelerator opening sensor 9 detects the opening of the accelerator. The driver depresses the accelerator to accelerate the vehicle. The accelerator depression amount corresponds to the magnitude of acceleration required by the driver. That is, the accelerator opening represents a value required by the driver for speed control. The accelerator opening sensor 9 outputs the detected accelerator opening to the vehicle controller 10.

  The vehicle controller 10 is a controller for controlling the entire vehicle system. The vehicle controller 10 acquires accelerator information and driving mode information using hardware such as a sensor. The vehicle controller 10 acquires the accelerator information by detecting the accelerator opening by using the accelerator opening sensor 9.

  The driving mode represents a control method of the vehicle system. The traveling mode is divided into a plurality of modes corresponding to the energy consumption rate of the vehicle, and the energy consumption amount with respect to the accelerator opening degree differs depending on the traveling mode. In an electric vehicle, the energy consumption corresponds to the power consumption of the battery 6. In this embodiment, the traveling mode is divided into an eco mode, a normal mode, and a sports mode. Further, the driver selects a traveling mode by switching a switch inside the vehicle. In the eco mode, the amount of energy consumption with respect to the accelerator opening is suppressed most. In the sports mode, the amount of energy consumed with respect to the accelerator opening is the largest and the acceleration operability is also high. The normal mode has both acceleration performance and reduction of energy consumption. The magnitude or rate of change of the torque generated by the generator 3 in response to the driver's acceleration request is the smallest in the eco mode and the largest in the sports mode. The vehicle controller 10 acquires the information on the driving mode by detecting the state of the switch for selecting the driving mode.

  The vehicle controller 10 acquires the information on the battery 6 from the battery controller 8 and acquires the information indicating the traveling state of the vehicle from the motor controller 7. The information indicating the traveling state of the vehicle is, for example, vehicle speed information.

  The vehicle controller 10 detects a speed control request from the driver using the accelerator opening sensor 9 and calculates a required torque based on the detected request and the vehicle state. The required torque is a value that represents the request for speed control from the driver by the magnitude of the torque generated by the generator 3. The vehicle controller 10 uses the driving force map stored in the memory 11 to calculate the required torque.

  FIG. 2 is a graph for explaining the driving force map. As shown in FIG. 2, the driving force map shows the correspondence relationship between vehicle speed, accelerator opening (APO), and required torque. In FIG. 2, the graph indicated by the solid line shows the characteristics of the required torque with respect to the vehicle speed, and the characteristics differ for each accelerator opening. If the driver requests a vehicle control (accelerator operation) while the vehicle is traveling at a certain vehicle speed, the graph corresponding to the accelerator opening is selected and the current vehicle speed is displayed on the selected graph. The required torque corresponding to is the driving force required for the generator 3. In FIG. 2, the positive value of the driving force indicates the output torque on the power running side (driving force of the generator 3), and the negative value of the driving force indicates the input torque on the regeneration side (braking force of the generator 3). There is.

In FIG. 2, areas A and B indicate areas in which the coasting control is executed. Graph R shows the characteristics of the running resistance line (R / L line). The running resistance line shows the torque required to maintain a constant vehicle speed, and is experimentally obtained. T 1 _{_ON} , T 2 _{_ON} , T 1 _{_OFF} and T 2 _{_OFF} are thresholds indicating the timing of switching the control mode between the normal control and the coasting control by torque, and are set in advance. T 1 _{_ON} and T 2 _{_ON} indicate threshold _values for switching from normal control to coasting control. _{T1_OFF} and _{T2_OFF} have shown the threshold value for switching from inertia running control to normal control. T 1 _{_ON} and T 1 _{_OFF} indicate threshold _values on the power running side, and T _{2 _ON} and T 2 _{_OFF} indicate threshold _values on the regeneration side. Note that the normal control, the coasting control, and the torque thresholds (T _{1_ON} , T _{2_ON} , T _{1_OFF} , T _{2_OFF} ) will be described later.

  The vehicle controller 10 acquires the motor rotation speed from the motor controller 7 and calculates the vehicle speed (control vehicle speed). The vehicle speed is calculated from the motor rotation speed, the gear ratio, and the wheel radius of the drive wheel 1. That is, the control vehicle speed corresponds to the motor rotation speed. Then, the vehicle controller 10 calculates the torque corresponding to the accelerator opening and the vehicle speed as the torque required by the driver while referring to the driving force map described above. The vehicle controller 10 outputs the calculated required torque to the motor controller 7. As will be described later, in normal control, the vehicle controller 10 outputs the required torque for control to the motor controller 7 without correcting the torque indicated by the driving force map. On the other hand, in the coasting control, the vehicle controller 10 corrects the torque shown in the driving force map to zero, and then outputs the corrected torque (zero torque) to the motor controller 7 as a required torque for control.

  Next, a method of torque control by the torque control device according to the present embodiment will be described with reference to FIG. FIG. 3 is a flowchart showing a control flow of the motor controller 7 and the vehicle controller 10. When the driver turns on the main switch, the control flow shown in FIG. 3 starts. The main switch switches the vehicle system on and off.

  In step S1, the vehicle controller 10 uses the accelerator opening sensor 9 to detect the current accelerator opening. The vehicle controller 10 acquires the motor rotation speed by acquiring the detection value of the rotation speed sensor 4 via the motor controller 7, and calculates the vehicle speed based on the acquired motor rotation speed. As a result, the vehicle controller 10 detects the vehicle speed.

  In step S2, the vehicle controller 10 acquires information on the driving mode.

  In step S3, the vehicle controller 10 calculates the required torque corresponding to the accelerator opening and the vehicle speed by referring to the driving force map.

In step S4, the vehicle controller 10 determines whether the traveling mode is the eco mode or the normal mode. When the traveling mode is the eco mode or when the traveling mode is the normal mode , the control flow proceeds to step S5. On the other hand, if the traveling mode is the sports mode, the control flow proceeds to step S10. That is, the coasting control described later is executed in the eco mode or the normal mode, but the coasting control is not executed in the sport mode.

In step S5, the vehicle controller 10 compares the calculated required torque with the torque threshold value ( _{T1_ON} , _{T2_ON} ), and determines whether to execute the inertia running control based on the comparison result. The vehicle controller 10 determines whether or not the required torque is within the torque range indicated by the area A. Region A is a range surrounded by the torque thresholds (T _{1_ON} , T _{2_ON} ) on the driving force map. When the required torque is within the range of the area A, the vehicle controller 10 determines to execute the coasting control. The control flow proceeds to step S6. On the other hand, when the required torque is outside the range of the area A, the vehicle controller 10 determines not to execute the coasting control. The control flow proceeds to step S11.

Whether or not the required torque is within the range of the area A is determined by comparing the required torque with the torque thresholds (T _{1_ON} , T _{2_ON} ) as _follows . When the calculated required torque is the torque on the power running side and the required torque is smaller than the torque threshold value ( _{T1_ON} ), the vehicle controller 10 determines to execute the coasting control. When the calculated required torque is the torque on the power running side and the required torque is equal to or greater than the torque threshold value (T 1 — _ON ), the vehicle controller 10 determines not to execute the coasting control. When the calculated required torque is the torque on the regeneration side and the required torque is smaller than the torque threshold value ( _{T2_ON} ), the vehicle controller 10 determines to execute the coasting control. When the calculated required torque is the torque on the regeneration side and the required torque is equal to or greater than the torque threshold value (T 2 — _ON ), the vehicle controller 10 determines not to execute the coasting control. As shown in FIG. 2, when the required torque on the regeneration side is represented by a negative value, the torque threshold value (T _{2_ON} ) is set to a negative torque value, and when the required torque> the torque threshold value (T _{2_ON} ) is satisfied, The vehicle controller 10 determines to execute coasting control.

In step S6, the vehicle controller 10 executes coasting control. In the inertia traveling control, when the required torque from the driver is within the area A, the required torque for control is set to zero, and the generator 3 is set so that the set required torque becomes the torque generated by the generator 3. Control. That is, when the required torque is smaller than the torque threshold (T _{1_ON} , T _{2_ON} ), the vehicle controller 10 determines the required torque (corresponding to the torque command value) used for controlling the generator 3 from the actual request from the driver. Is also lowered to control the generator 3.

  When the generator 3 generates the torque as requested by the driver when the required torque is small, the power consumption of the electric system such as the inverter 5 is relatively larger than the driving power of the generator 3. I will end up. That is, when the generator 3 is driven as requested by the driver, the operating efficiency becomes low. Further, if the traveling time is accumulated in the state where the required torque is small, the operating time in the state where the efficiency is low becomes long, and as a result, the cruising distance of the vehicle is reduced.

  The torque control device according to the present embodiment sets the required torque for control to zero when the required torque from the driver is within the region A, and the set required torque becomes the torque generated by the generator 3. The generator 3 is controlled. Therefore, the torque generated by the generator 3 becomes lower than the torque required by the driver, so that the generator 3 can be prevented from being driven in a low efficiency state, and the operating efficiency can be improved.

  In step S7, the vehicle controller 10 detects the accelerator opening and the vehicle speed. In step S8, the vehicle controller 10 calculates the required torque. The control flow of steps S7 and S8 is the same as the control flow of steps S1 and S3. That is, the vehicle controller 10 detects the accelerator opening and the vehicle speed even during the coasting control, and calculates the required torque from the driver.

In step S9, the vehicle controller 10 compares the calculated required torque with the torque threshold value ( _{T1_OFF} , _{T2_OFF} ), and determines whether or not to cancel the coasting control based on the comparison result. The vehicle controller 10 determines whether or not the required torque is within the torque range indicated by the area B. The area B is a range surrounded by the torque thresholds (T _{1_OFF} , T _{2_OFF} ) on the driving force map. When the required torque is within the range of the region B, the vehicle controller 10 determines to continue the inertia running control. The control flow returns to step S6. On the other hand, when the required torque is outside the range of the area B, the vehicle controller 10 determines to cancel the coasting control. The control flow proceeds to step S11.

Whether or not the required torque is within the range of the region B is determined by comparing the required torque with the torque thresholds (T _{1_OFF} , T _{2_OFF} ) as _follows . When the calculated required torque is the torque on the power running side and the required torque is smaller than the torque threshold value (T 1 — _OFF ), the vehicle controller 10 determines not to cancel the coasting control. When the calculated required torque is the torque on the power running side and the required torque is equal to or _larger than the torque threshold (T 1 — _OFF ), the vehicle controller 10 determines to cancel the coasting control. When the calculated required torque is the torque on the regeneration side and the required torque is smaller than the torque threshold value ( _{T2_OFF} ), the vehicle controller 10 determines not to cancel the coasting control. When the calculated required torque is the torque on the regeneration side and the required torque is equal to or greater than the torque threshold (T 2 — _OFF ), the vehicle controller 10 determines to cancel the inertia traveling control. As shown in FIG. 2, when the required torque on the regeneration side is represented by a negative value, the torque threshold value (T _{2_OFF} ) is set to a negative torque value, and when the required torque> the torque threshold value (T _{2_OFF} ) is satisfied, The vehicle controller 10 determines to cancel the coasting control.

  When it is determined in step S5 that the inertia traveling control is not to be executed, the vehicle controller 10 executes the normal control in step S11. In the normal control, the vehicle controller 10 controls the generator 3 so that the required torque calculated on the driving force map becomes the generated torque of the generator 3.

  In step S11, the vehicle controller 10 determines whether or not the main switch is off. If the main switch is in the ON state, the control flow returns to step S1. If the main switch is OFF, the control flow ends.

  The relationship between the required torque and the inertia running control will be described with reference to FIG. FIG. 4 is a graph showing the peripheral portion of the area A in the driving force map shown in FIG.

As shown in FIG. 4, the torque threshold (T _{1_ON} ) on the power running side increases as the vehicle speed increases. On the other hand, the torque threshold value ( _{T2_ON} ) on the regeneration side is a substantially constant value regardless of the vehicle speed. That is, when the torque difference at any vehicle speed (V _a1 , V _a2 , V _a3 : where V _a1 <V _a2 <V _a3 ) in the region A is ΔTr ₁ , ΔTr ₂ , ΔTr ₃ , Regarding the torque difference (ΔTr ₁ , ΔTr ₂ , ΔTr ₃ ), ΔTr ₃ is the largest and ΔTr ₁ is the smallest. The torque difference (ΔTr ₁ , ΔTr ₂ , ΔTr ₃ ) indicates the range in which the coasting control is executed for a certain vehicle speed. That is, the higher the vehicle speed, the wider the execution range of the coasting control.

  When the motor rotation speed is high, the power consumption of the electric system such as the inverter 5 is larger than the power consumption required to drive the generator 3 when the motor rotation speed is low. . Generally, when the motor rotation speed is high, the inverter 5 is controlled by the field weakening control method in order to suppress the counter electromotive force generated in the generator 3. However, when the inverter is controlled by the field weakening control method, the power consumption of the inverter becomes larger than that in the normal inverter control. In the present embodiment, the torque threshold value is set such that the execution range of the inertia traveling control becomes wider as the vehicle speed becomes higher. When the required torque from the driver is small in a state where the motor rotation speed is large, the inertia traveling control is executed, and thus it is possible to avoid drive control in which the generator 3 outputs torque under high rotation. As a result, inefficient driving of the generator 3 can be suppressed.

Further, the torque threshold value ( _{T2_ON} ) on the regeneration side is set to a substantially constant value regardless of the vehicle speed. Unlike the present embodiment, when the torque threshold value ( _{T2_ON} ) on the regeneration side changes according to the magnitude of the vehicle speed, the regenerative torque changes according to the vehicle speed, so the deceleration of the vehicle becomes the vehicle speed. It will change accordingly. That is, the deceleration when the accelerator opening becomes zero when the vehicle is traveling at high speed and the deceleration when the accelerator opening becomes zero when the vehicle is traveling at low speed are different. Will end up. Then, due to the different deceleration, the driver cannot predict how much the deceleration will be in relation to the current vehicle state, and will be in a difficult state to drive. In the present embodiment, the torque threshold value ( _{T2_ON} ) on the regeneration side is set to a constant value regardless of the magnitude of the vehicle speed, so that the driver can be prevented from feeling uncomfortable.

Further, as shown in FIG. 4, the region A is set to a range in which the vehicle speed is at least the lower limit value V _L or more. That is, when the vehicle speed is equal to or higher than the lower limit value _VL , the coasting control is executed according to the magnitude of the required torque. On the other hand, when the vehicle speed is less than the lower limit value _VL , the inertia traveling control is not executed regardless of the magnitude of the required torque. That is, in a driving area where the vehicle speed is less than the lower limit value _VL, there are many scenes where a small torque is required, for example, when parking is stopped in a parking space. Therefore, in the present embodiment, the vehicle controller 10 does not execute the coasting control when the motor rotation speed is smaller than the predetermined rotation speed threshold value. As a result, in a driving scene where a small torque is required, the torque required by the driver can be output. The predetermined rotation speed threshold value is a threshold value corresponding to the lower limit value (V _L ) of the vehicle speed.

Further, as shown in FIG. 2, the torque threshold value (T _{1_OFF} ) is set to a value larger than the torque threshold value (T _{1_ON} ). Further, the torque threshold value (T _{2_OFF} ) is set to a value larger than the torque threshold value (T _{2_ON} ) (a value larger on the minus side). Accordingly, it is possible to prevent a phenomenon (hunting) in which the control mode is frequently switched between the normal control and the coasting control.

Further, as shown in FIG. 2, the torque threshold value (T 1 _—ON ) is set to a value lower than the torque indicated by the characteristic of the running resistance line (R / L line). The torque indicated by the characteristics of the running resistance line (R / L line) is the torque required to maintain a constant vehicle speed. For example, in the map shown in FIG. 2, it is assumed that the driver depresses the accelerator while the vehicle is stopped and the vehicle accelerates at an accelerator opening of 20%. When the vehicle speed increases while maintaining the accelerator opening of 20%, the required torque decreases along the graph of the accelerator opening of 20% in the driving force map. Then, when the required torque reaches the intersection point Q, the driving force and the running resistance are in balance, and the vehicle speed becomes a constant speed (Vq). The intersection Q is the intersection of the graph of 20% accelerator opening and the running resistance line (R / L line). The torque threshold value ( _{T1_ON} ) corresponding to the speed Vq is set to a value lower than the torque indicated by the intersection Q. Further, the torque threshold value ( _{T1_ON} ) is set to a value lower than the torque indicated by the characteristic of the running resistance line (R / L line) not only at the speed Vq but also at other speeds.

  When it is desired to increase the vehicle speed, the vehicle controller 10 executes the normal control, and the required torque for control matches the required torque from the driver (torque at the time of acceleration request). On the other hand, when it is desired to reduce the vehicle speed by reducing the required torque, the vehicle controller 10 executes the coasting control, and the required torque for control is set to zero. As a result, when it is desired to reduce the required torque and reduce the vehicle speed while responding to the acceleration request from the driver, it is possible to prevent the generator 3 from being driven in a low efficiency state and improve the operation efficiency.

Next, with reference to FIG. 5, a method of switching between the normal control and the coasting control will be described with reference to an actual vehicle operation example. FIG. 5 is a graph showing the peripheral portion of the area A in the driving force map shown in FIG. Note that the torque threshold value (T _{1_ON} ) and the torque threshold value (T _{1_OFF} ) are set to the same value for ease of explanation. Note that "S1" to "S5" shown in FIG. 5 correspond to steps S1 to S5 in the following description, respectively.

  In step S1, when the brake pedal is turned off from the state where the vehicle is stopped, creep running is started.

  In step S2, the driver depresses the accelerator pedal to start acceleration with the accelerator opening being 30%.

  In step S3, the accelerator pedal is depressed and a surplus driving force is generated to continue acceleration. When the driving force and the running resistance are balanced, the vehicle speed becomes constant.

In step S4, when the driving force and the running resistance are in equilibrium, as a deceleration request from the driver, the driver slightly loosens the accelerator to change the accelerator opening from 30% to 20%. At the timing of releasing the accelerator (accelerator release timing), the required torque from the driver becomes smaller than the torque threshold value (T 1 — _ON ), so that the control mode of the generator 3 switches from the normal control to the coasting control. Then, when the inertia traveling control is started, the required torque for control is set to zero.

In step S5, if the accelerator opening is maintained at 20%, the required torque calculated on the driving force map becomes _{equal to} or greater than the torque threshold (T _{1_OFF} ), so the control mode of the generator 3 is coasting. Switch from control to normal control. Also, the required torque changes along the graph above the accelerator opening of 20%, and when the driving force and the running resistance are balanced, the vehicle speed becomes a constant speed.

  As described above, when the control mode is switched from the normal control to the inertia traveling control, the required torque for control changes from the torque value calculated on the driving force map to zero. At this time, when the required torque for control is changed discontinuously, the change in driving force (braking force during regeneration) becomes large, which may give the driver a feeling of strangeness. Therefore, in the present embodiment, the torque rate limiter is set to prevent such a feeling of strangeness.

  Hereinafter, the torque rate limiter will be described with reference to FIGS. 6 and 7. 6 and 7 are time charts for turning on and off the coasting control and graphs showing torque characteristics. FIG. 6 shows the characteristics on the power running side, and FIG. 7 shows the characteristics on the regeneration side. In FIGS. 6 and 7, the graph a shows the required torque calculated using the driving force map, and the graph b shows the required torque for control. The torque change indicated by the graph A corresponds to the accelerator operation.

From time 0 to time t ₁ , the required torque changes in a region larger than the torque threshold value (T _{1_ON} ) due to the accelerator operation, so the control mode of the generator 3 is normal control.

While the vehicle is traveling, at time t _1, when the operation of the driver loosens the accelerator, the requested torque is decreased. The driving force of the generator 3 decreases so as to match the required torque from the driver.

At time t _2, the torque demand from the driver is smaller than the torque threshold (T _{1_ON),} the control mode of the generator 3 is switched from the normal control to the coasting control. At this time, if the generator 3 is controlled so that the driving force becomes zero, a sudden torque fluctuation occurs, which gives the driver a feeling of strangeness (bounce back to drivability). For this reason, the torque rate limiter is enabled between the time t ₂ and the time t ₃ to suppress the torque change amount.

From time t ₂ to time t ₃ , the vehicle controller 10 calculates the amount of change in the accelerator opening, and sets the amount of change in torque according to the calculated amount of change in the accelerator opening. The amount of change in torque is the amount of change until the required torque for control changes to zero at time t ₂ . The vehicle controller 10 calculates the torque change amount such that the torque change amount increases as the change amount of the accelerator opening (corresponding to the accelerator operation amount) increases. The vehicle controller 10 corrects the required torque for control so that the required torque for control changes with the calculated torque change amount, and outputs it to the motor controller 7. As a result, the torque change time becomes shorter as the torque change amount becomes larger, and the torque change time becomes longer as the torque change amount becomes smaller. The torque change time is the time until the driving force changes from the required torque value on the driving force map to zero, and is the time from time t ₂ to time t ₃ shown in FIGS . 6 and 7 .

At time _{t 3,} the control torque becomes smaller than the torque threshold _{(T L1_OFF),} the vehicle controller 10 cancels the torque rate limiter. The torque threshold value (T _{L1 — OFF} ) indicates the upper limit value of the invalid region of the torque rate limiter. The ineffective region of the torque rate limiter indicates a range where the control torque is zero without limiting the torque change. Invalid area, while containing the zero torque range between the upper limit value _{(T L1_OFF)} and the lower limit value _{(T L2_OFF).} When the driving force is close to 0, even if the control torque is changed to zero, the amount of change in acceleration is small and the influence on driving is small. Therefore, when the control torque is smaller than the torque threshold value ( _{TL1_OFF} ), the vehicle controller 10 removes the restriction on the torque change and sets the control torque to zero. Thereby, the inertia running time can be lengthened. The inertia running time is the time when the driving force (or the braking force) becomes zero, and is the time from time t ₃ to time t ₄ shown in FIGS . 6 and 7 .

It increases the required torque from the driver, at time t _4, when the required torque is greater than the torque threshold (T _{1_OFF),} the control mode of the generator 3 is switched to the normal control from the coasting control. When the control torque becomes larger than the torque threshold value ( _{TL1_OFF} ), the vehicle controller 10 enables the torque rate limiter.

Between times t ₄ from the time t _5, the vehicle controller 10 calculates the amount of change in the accelerator opening, set the amount of change in torque according to a change amount of the calculated accelerator opening. The vehicle controller 10 corrects the required torque for control so that the required torque for control changes with the set torque change amount, and outputs it to the motor controller 7. Then, at time t ₅ , the required torque from the driver matches the required torque for control.

The amount of change in the accelerator opening before and after time t ₄ is smaller than the amount of change in the accelerator opening before and after time t ₂ . Therefore, the torque change amount calculated during time t ₅ from the time t ₄ is smaller than the torque variation amount calculated during the time t ₂ time t _3. When the accelerator operation amount is small, the driver feels uncomfortable with a small torque change. In the present embodiment, in order to prevent such a feeling of strangeness, the torque change amount is reduced and the torque change time is lengthened.

Unlike the example of FIG. 6, the amount of change in the accelerator opening before and after the time t ₄ is the greater than the change amount of the accelerator opening degree before and after the time t _2, between the time t ₄ of time t ₅ The calculated torque change amount is larger than the torque change amount calculated between time t ₂ and time t ₃ . When the accelerator operation amount is large, it is difficult to feel a sense of discomfort with respect to the torque change. Therefore, the torque change amount is increased and the torque change time is shortened. As a result, the response time from the torque request to the torque output can be shortened, and control can be performed without delay in response to accelerator operation.

  Next, a torque rate limiter during regeneration will be described with reference to FIG.

Since the required torque changes in a region larger than the torque threshold value (T 2 _{_ON} ) from time 0 to time t ₁ , the control mode of the generator 3 is normal control. At time t ₁ , the required torque on the regeneration side decreases.

At time t _2, the torque demand from the driver is smaller than the torque threshold (T _{2_ON),} the control mode of the generator 3 is switched from the normal control to the coasting control. At this time, similarly to the power running side described above, the vehicle controller 10 enables the torque rate limiter to calculate the required torque for control.

From time t ₂ to time t ₃ , the vehicle controller 10 calculates the amount of change in the accelerator opening, and sets the amount of change in torque according to the calculated amount of change in the accelerator opening. The vehicle controller 10 corrects the required torque for control so that the required torque for control changes with the set torque change amount, and outputs it to the motor controller 7.

When the required torque on the regenerative side becomes large and the required torque becomes larger than the torque threshold value (T _{2 _OFF} ) at time t ₄ , the control mode of the generator 3 is switched from the inertia traveling control to the normal control. When control torque is higher than the torque threshold _{(T L 2 _OFF),} the vehicle controller 10 to enable torque rate limiter.

Between times t ₄ from the time t _5, the vehicle controller 10 calculates the amount of change in the accelerator opening, set the amount of change in torque according to a change amount of the calculated accelerator opening. The vehicle controller 10 calculates the required torque for control so that the required torque for control changes with the set torque change amount, and outputs it to the motor controller 7. Then, at time t ₅ , the required torque from the driver matches the required torque for control.

In the present embodiment, in order to improve the energy consumption rate, the torque thresholds ( _{T1_ON} , _{T1_OFF} , _{T2_ON} , _{T2_OFF} ) are switched according to the traveling mode. Hereinafter, the switching control of the torque threshold according to the traveling mode will be described using the torque characteristics in the normal mode and the torque characteristics in the eco mode. FIG. 8 is a graph showing torque characteristics in the normal mode, and FIG. 9 is a graph showing torque characteristics in the normal mode and torque characteristics in the eco mode. In FIG. 8, a graph a shows the required torque calculated using the driving force map, and a graph b shows the required torque for control. In FIG. 9, a graph a shows the required torque calculated using the driving force map, a graph b _n shows the required torque for control in the normal mode, and a graph b _e shows the required torque for control in the eco mode. Shows the required torque of.

The memory 11 stores at least two types of torque threshold _values (T 1 — _ON ). Further, at least two types of torque thresholds (T 1 — _OFF ), at least two types of torque thresholds (T 2 — _ON ), and at least two types of torque thresholds (T 2 — _OFF ) are stored in the memory 11, respectively. One of the two types of torque thresholds (T _{1n_ON} , T _{1n_OFF} , T _{2n_ON} , T _{2n_OFF} ) is the threshold selected in the normal mode. Of the two types of torque thresholds, the other torque threshold (T _{1e_ON} , T _{1e_OFF} , T _{2e_ON} , T _{2e_OFF} ) is the threshold selected in the eco mode. Torque threshold _{(T 1e_ON)} is greater than the torque threshold _{(T 1n_ON),} torque threshold _{(T 1e_OFF)} is greater than the torque threshold _{(T 1n_OFF).} The torque threshold _{(T 2e_ON)} is greater than the torque threshold _{(T 2n_ON),} torque threshold _{(T 2e_OFF)} is greater than the torque threshold _{(T 2n_OFF).}

When the traveling mode is the normal mode, the vehicle controller 10 _selects the torque thresholds (T _{1n_ON} , T _{1n_OFF} , T _{2n_ON} , T _{2n_OFF} ) for the normal mode. When the traveling mode is the eco mode, the vehicle controller 10 _selects the torque thresholds (T _{1e_ON} , T _{1e_OFF} , T _{2e_ON} , T _{2e_OFF} ) for the eco mode.

  It is assumed that when the traveling mode is the normal mode, the required torque from the driver changes due to the accelerator operation with the characteristics shown in the graph а of FIG.

When the required torque from the driver becomes smaller than the torque threshold value (T _{1n_ON} ) at time t _1n , the vehicle controller 10 switches the control mode of the generator 3 from the normal mode to the coasting control.

At time _{t 2n,} the torque required for the control is less than the torque threshold _{(T L1_OFF),} the vehicle controller 10 cancels the torque rate limit.

When the required torque from the driver becomes larger than the torque threshold value (T _{2n_OFF} ) at time t _3n , the vehicle controller 10 activates the torque rate limit and switches the control mode of the generator 3 from coasting control to normal control. .

When the required torque from the driver becomes smaller than the torque threshold value (T _{2n_ON} ) at time t _4n , the vehicle controller 10 switches the control mode of the generator 3 from normal control to coasting control.

At time _{t 5n,} when the required torque for the control is less than the torque threshold _{(T L2_OFF),} the vehicle controller 10 cancels the torque rate limit.

When the required torque from the driver becomes larger than the torque threshold value (T _{1n_OFF} ) at time t _6n , the vehicle controller 10 enables the torque rate limit and switches the control mode of the generator 3 from coasting control to normal control. .

The inertia running time in the normal mode is the time from time t _2n to time t _3n shown in FIG. 8 and the time from time t _5n to time t _6n shown in FIG.

  Next, it is assumed that when the traveling mode is the eco mode, the required torque from the driver changes with the characteristic as shown by the graph а in FIG. 9 by the accelerator operation. The characteristic of the torque demanded by the driver shown in the graph a of FIG. 9 is the same as the characteristic shown in the graph a of FIG.

The content of control at each time point from time t _1e to time t _{6e is} the same as the content of control at each time point from time t _1n to time t _6n . On the other hand, since the selected torque threshold differs between the eco mode and the normal mode, the timing of switching the control mode of the generator 3 also differs.

Eco mode of torque threshold _{(T 1e_ON)} is greater than the normal mode of torque threshold _{(T 1n_ON).} Therefore, in power running, the timing (time t _1e ) at which the normal control is switched to the coasting control in the eco mode is earlier than the timing (time t _1n ) at which the normal control is switched to the coasting control in the normal mode.

Eco mode of torque threshold _{(T 2e_OFF)} is greater than the normal mode of torque threshold _{(T 2n_OFF).} Therefore, in regeneration, the timing (time t _3e ) at which the coasting control is switched to the normal control in the eco mode is later than the timing (time t _3n ) at which the coasting control is switched to the normal control in the normal mode. Thereby, when switching from power running to regeneration, the inertia running time in the eco mode becomes longer than in the normal mode.

In addition, Eco mode of torque threshold _{(T 2e_ON)} is greater than the normal mode of torque threshold _{(T 2n_ON).} Therefore, in regeneration, the timing (time t _4e ) at which the normal control is switched to the coasting control in the eco mode is earlier than the timing (time t _4n ) at which the normal control is switched to the coasting control in the normal mode.

Eco mode of torque threshold _{(T 1e_OFF)} is greater than the normal mode of torque threshold _{(T 1n_OFF).} Therefore, in power running, the timing (time _t6e ) at which the coasting control is switched to the normal control in the eco mode is later than the timing (time _t6n ) at which the coasting control is switched to the normal control in the normal mode. As a result, when switching from regeneration to power running, the inertia running time in the eco mode becomes longer than in the normal mode.

  When the sport mode is selected, acceleration operability is emphasized, so the vehicle controller 10 prohibits coasting control.

As described above, in the present embodiment, the request for speed control from the driver is detected using the accelerator opening sensor 9, the required torque is calculated based on the state of the vehicle and the detected request, and the required torque is calculated based on the required torque. The torque generated by the generator 3 is controlled. When the calculated required torque is smaller than the torque threshold value ( _{T1_ON} , _{T2_ON} ), the required torque is set to zero and the generator 3 is controlled based on the set required torque. When the generator 3 is driven according to the request from the driver, the coasting control is performed by setting the required torque for control to zero in the drive region where the operation efficiency is not good. As a result, inefficient driving of the generator 3 can be suppressed, and the driving efficiency of the vehicle can be improved.

Further, in this embodiment, it is greater than the generator 3 of the torque threshold (T _{1_ON)} when the rotational speed is greater than a predetermined value when the rotational speed of the generator 3 is smaller than the predetermined value torque threshold (T _{1_ON).} When the rotation speed of the generator 3 is high, the operating efficiency is poor as compared to when the rotation speed of the generator 3 is low. Therefore, the torque threshold (T _{1_ON} ) on the high rotation side is made larger than (T _{1_ON} ) on the low rotation side, and the range in which the inertia traveling control is executed is widened on the high rotation side, thereby making the generator 3 inefficient. Driving can be suppressed.

  Here, the loss and efficiency of the generator 3 will be described with reference to FIGS. 10 and 11. FIG. 10 is a graph showing the characteristics of power loss with respect to the rotation speed of the generator 3. FIG. 11 is a graph showing a characteristic of efficiency with respect to the rotation speed of the generator 3. The graphs of FIGS. 10 and 11 show different characteristics depending on the magnitude of a constant drive torque.

  As shown in FIG. 10, when the generator 3 is driven at a constant carrier frequency, the power loss increases in proportion to the rotation speed and the driving torque, respectively. The loss of the generator 3 mainly includes copper loss, iron loss, and mechanical loss. Copper loss is a loss caused by electric resistance (winding resistance) of a copper wire used for winding a coil. Iron loss is a loss caused by a coil iron core, and is mainly a sum of hysteresis loss and eddy current loss. Mechanical loss is a loss due to friction and a loss due to air resistance. Friction is generated in the bearing portion due to the rotation of the generator 3. The air resistance is the air resistance generated by the bearing of the rotor and the air resistance generated by the rotation of the rotor.

  When the torque is constant, the power loss increases with the locus of the quadratic curve with respect to the rotation speed of the generator 3. On the other hand, when the torque is constant, the drive output of the generator 3 increases in proportion to the rotation speed of the generator 3. Therefore, with the torque kept constant, the larger the number of revolutions, the larger the increase in power loss compared to the increase in drive output.

  That is, as shown in FIG. 11, when the drive state of the generator 3 is high speed (high rotation speed or high vehicle speed) and low torque, the efficiency is low. Further, when the rotation speed of the generator 3 is in the medium speed to high speed region, a back electromotive force is generated in the generator 3. Then, in order to output the torque while suppressing the counter electromotive force, the field weakening control is required, and the loss due to the field weakening control also causes a decrease in efficiency.

In the present embodiment, as described above, the torque threshold value on the high rotation side (T _{1_ON} ) is set to a value larger than the torque threshold value on the low rotation side (T _{1_ON} ). That is, the torque threshold value is set so that the execution range of the coasting control is wide in the operating region of the generator 3 at low torque and high rotation. As a result, the time during which the generator 3 is in the inefficient state can be shortened, and the drive efficiency of the generator 3 can be improved.

Moreover, in this embodiment, inertia running control is performed when the rotation speed of the generator 3 is larger than a predetermined rotation speed threshold value, and coasting control is performed when the rotation speed of the generator 3 is smaller than the predetermined rotation speed threshold value. Do not execute. The predetermined rotation speed threshold value is a value obtained by converting the lower limit value ( _VL ) shown in FIG. 4 into a rotation speed. That is, in the operating region smaller than the rotation speed threshold value, when the required torque from the driver is small, the generator 3 can generate the torque as the required torque. As a result, the torque required by the driver can be output from the generator 3 in a driving scene where a small torque is likely to be required.

In this embodiment also, the required torque is a torque threshold _{(T 1_OFF,} T _{2_OFF)} smaller state from the torque threshold _{(T 1_OFF,} T _{2_OFF)} the torque change rate when changing to a larger state, the magnitude of the required torque Set accordingly. In the present embodiment, the required torque is a torque threshold _{(T 1_ON,} T _{2_ON)} torque threshold _{(T 1_ON,} T _{2_ON)} from larger state torque change rate when changed to a smaller state, according to the magnitude of the required torque To set. That is, when the control mode is switched between coasting control and normal control, the torque change rate is set according to the magnitude of the torque demanded by the driver. When the required torque is small, it is possible to suppress the torque change due to the change of the control mode. Therefore, it is possible to suppress a sudden change in torque and provide the driver with a natural ride comfort. When the required torque is large, the generated torque of the generator 3 is changed with high responsiveness to the change in the required torque when the control mode is changed. As a result, it is possible to perform control so that there is no delay in the response to the accelerator operation.

  Further, in the present embodiment, a traveling mode is selected from a plurality of traveling modes, a torque threshold is selected according to a traveling mode selected from the plurality of torque thresholds, and the required torque is greater than the selected torque threshold. When it is smaller, the coasting control is executed. As a result, it is possible to set the torque threshold value according to the traveling mode while coping with the traveling modes having different energy consumption rates, so that the driving efficiency of the vehicle can be improved.

As a modified example of the present embodiment, in order to prevent hunting in the control mode, even if the normal control is switched to the coasting control when the state where the required torque is within the execution range of the coasting control continues for a certain time or more. Good. Specifically, the vehicle controller 10 calculates the required torque from the driver using the drive map, and measures the time when the calculated required torque becomes smaller than the torque threshold (T _{1_ON} , T _{2_ON} ). . The vehicle controller 10 continues the measurement when the calculated required torque continues to be smaller than the torque threshold value (T _{1_ON} , T _{2_ON} ). The vehicle controller 10 executes coasting control when the measured time is equal to or longer than a predetermined time threshold value. As a result, hunting can be prevented while accurately grasping the traveling scene in which the required torque for control is to be corrected by inertial traveling control. When the control for preventing hunting is performed by the time as described above, the torque thresholds ( _{T1_ON} , _{T2_ON} ) and the torque thresholds ( _{T1_OFF} , _{T2_OFF} ) may be the same value or different values.

1 ... Drive wheel 2 ... Differential gear 3 ... Generator (MG: motor)
4 ... Revolution sensor 5 ... Inverter 6 ... Battery 7 ... Motor controller 8 ... Battery controller 9 ... Accelerator opening sensor 10 ... Vehicle controller 11 ... Memory

Claims (8)

In the torque control method for controlling the torque of the motor,
The sensor is used to detect the speed control request from the driver,
Calculate the required torque based on the request,
Controlling the torque generated by the motor based on the required torque,
When the required torque is smaller than a predetermined torque threshold value, the required torque is set to zero, and inertia running control for controlling the motor based on the set required torque is executed.
The predetermined torque threshold value when the rotation speed of the motor is higher than a first rotation speed threshold value is larger than the predetermined torque threshold value when the rotation speed of the motor is lower than the first rotation speed threshold value. The torque control method according to claim 1, wherein the predetermined torque threshold value is lower than a torque required to maintain a constant vehicle speed. The predetermined torque threshold, the torque control method according to claim 1 or 2 is set to a constant value at the regeneration side. When the rotation speed of the motor is larger than a second rotation speed threshold value, the coasting control is executed,
When the rotation speed of the motor is less than the second rotational speed threshold value, the torque control method according to claim 1 which does not execute the coasting control. A torque change rate when the required torque changes from a state smaller than the predetermined torque threshold to a state larger than the predetermined torque threshold, or the predetermined torque threshold from a state where the required torque is larger than the predetermined torque threshold The torque control method according to any one of claims 1 to 4 , wherein a torque change rate in the case of changing to a smaller state is set according to the magnitude of the required torque. The torque control method according to any one of claims 1 to 5 , wherein the inertia traveling control is executed when a state in which the required torque is smaller than the predetermined torque threshold value continues for a certain time or more. The traveling mode of the vehicle equipped with the motor is selected from a plurality of traveling modes,
From the plurality of torque thresholds, select the torque threshold according to the selected running mode,
If the required torque is smaller than the selected said torque threshold value, the torque control method according to any one of claims 1 to 6 to perform the coasting control. An accelerator opening sensor that detects the accelerator opening,
A rotation speed sensor that detects the rotation speed of the motor,
A memory for storing a map showing a relative relationship between the torque of the motor, the rotational speed, and the accelerator opening degree;
A controller for controlling the motor,
The controller is
While referring to the map, the torque corresponding to the accelerator opening and the rotational speed is calculated as a required torque from the driver,
When the required torque is larger than a predetermined torque threshold value, the generated torque generated by the motor is controlled to match the required torque,
When the required torque is smaller than the predetermined torque threshold, the required torque is set to zero, and the motor is controlled so that the generated torque becomes zero.
The predetermined torque threshold value when the rotation speed of the motor is higher than a first rotation speed threshold value is larger than the predetermined torque threshold value when the rotation speed of the motor is lower than the first rotation speed threshold value.

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